Hi,I am using using Ulead Multimedia studio 6.5. when I created vcd using frame base the quality is not good. I do not understand difference between frame and field thing. what should i do to create a good quality vcd viewable without any distortion in picture quality on tv. Thank you.

-- rajiv kumar (rajeevguglani@hotmail.com), May 20, 2002

Answers

When u watch a normal TV program on a typical TV you see a frame which is made up of two interlaced fields. There are two fields in a frame and the first field displayed is the leading or dominant field. So in PAL, you see 25 frames/sec, so it follows there are 50 fields/sec. After the first field is displayed the second field is displayed with its lines in between (interlaced) the preceding one, giving us a perceived resolution higher than that afforded a single field (twice in fact) using the same bandwidth for just a single field. This is one basic of television. Most transmission and packaged systems digital and analogue use this conventional interlaced strandard, like VHS, LaserDisc, TV broadcasts, DVD, and SVCD, and other MPEG-2-based systems. It then becomes important to determine and stay all the way with correct field ordering when working with any of these media because it is easy to reverse this order at any point in the chain and create shaky, shuddering pictures. If u start with a field-based (interlaced) media and intend to output the same naturally u choose field. VCD is unique in this because to save bandwidth and maintain the bitrate to about 1.4MB/s it was decided early on in White Book to just use one field. This field can be just one of the fields in a frame (the other discarded, which is mainly what the Panasonic encoder does), or better, to intelligently interpolate the two existing fields from the source to create one unique field (an array of choices to do this in TMPGenc). It is just as important in the creation of an MPEG-1 stream for VCD, if the source is normal interlaced video, to see to it that the encoder is reading the correct field order (most especially if interpolation is done). On playback of an MPEG-1 stream this one field is merely shown twice to recreate the frame. Note therefore that unlike the normal interlaced source where the two fields in a frame are uniquely different, on VCD both fields are identical, leading to such things like jaggies in the picture on slanted lines (a noticeable VCD limitation). Since fields do not have that much relevance in the end product choose frames. At the same time note that the MPEG encoding engine of ULead Video is Ligos LSX which noted for its so-so quality. That is probably your main problem. Best you export to an AVI file then encode the same with TMPGenc.

-- Mehmet Tekdemir (turk690@yahoo.com), May 22, 2002.

hats off to you Mehmet, you have really mastered videos.

~m

-- ~m (mtekayo@yahoo.com), May 23, 2002.